• Forty-nine people were killed in shootings at two mosques in central Christchurch, New Zealand, on Friday, in a terrorist attack that appeared to have been carried out by a white nationalist extremist who posted a racist manifesto online and streamed live video of the attacks on Facebook.

• Forty-nine people were killed in shootings at two mosques in central Christchurch, New Zealand, on Friday, in a terrorist attack that appeared to have been carried out by a white nationalist extremist who posted a racist manifesto online and streamed live video of the attacks on Facebook.

• A 28-year-old man from Australia was charged with murder and was to appear Saturday morning in a Christchurch courtroom. Court papers identified him as Brenton Tarrant. The New Zealand police said he would face additional charges.

• Prime Minister Jacinda Ardern described the assault as “an extraordinary and unprecedented act of violence,” and promised changes in New Zealand’s gun laws.

• Prime Minister Jacinda Ardern described the assault as “an extraordinary and unprecedented act of violence,” and promised changes in New Zealand’s gun laws.

• President Trump, who was cited in the manifesto as a source of inspiration, told reporters he did not see white nationalism as a rising threat around the world and attributed such attacks to “a small group of people that have very, very serious problems.” He also said he had not seen the manifesto.

• President Trump, who was cited in the manifesto as a source of inspiration, told reporters he did not see white nationalism as a rising threat around the world and attributed such attacks to “a small group of people that have very, very serious problems.” He also said he had not seen the manifesto.

• Officials said a 28-year-old man had been charged with murder, and that two explosive devices were found attached to a vehicle that they had stopped. The man’s name was not immediately released.

The attacker targeted the Al Noor Mosque in the center of the city and Linwood Mosque, about three miles away.

The attacker targeted the Al Noor Mosque in the center of the city and Linwood Mosque, about three miles away.

The country’s police commissioner, Mike Bush, said at a Friday evening news conference that 41 people had been killed at Al Noor Mosque and seven at Linwood Mosque, and that another victim had died at Christchurch Hospital.

The country’s police commissioner, Mike Bush, said at a Friday evening news conference that 41 people had been killed at Al Noor Mosque and seven at Linwood Mosque, and that another victim had died at Christchurch Hospital.

David Meates, the chief executive of the Canterbury District Health Board, said that 48 people, including young children, were treated for injuries at the hospital. He said the injuries included gunshot wounds and ranged from critical to minor. Mr. Bush said Saturday morning that two of the victims were in critical condition.

David Meates, the chief executive of the Canterbury District Health Board, said that 48 people, including young children, were treated for injuries at the hospital. Mr. Bush said Saturday morning that two of the victims were in critical condition.

The police said Friday that three men and one woman had been taken into custody, but Mr. Bush lowered the total number to three on Saturday morning, indicating that someone had been released.

The police said Friday that three men and one woman had been taken into custody, but Mr. Bush lowered the total number to three on Saturday morning, indicating that someone had been released.

Mr. Bush said that a 28-year-old man had been charged with murder and would appear in Christchurch court on Saturday morning. A number of firearms were recovered from the scenes of the shootings, he said.

Ms. Ardern said none of those detained had been on security watch lists.

Ms. Ardern said none of those detained had been on security watch lists.

Mr. Bush had earlier urged people not to go to mosques anywhere in New Zealand on Friday. He also urged mosques nationally to “close your doors until you hear from us again.”

Mr. Bush had earlier urged people not to go to mosques anywhere in New Zealand on Friday. He also urged mosques nationally to “close your doors until you hear from us again.”

A 17-minute video posted to Facebook shows part of the attack.

A 17-minute video posted to Facebook shows part of the attack.

The clip, which may have been taken from a helmet camera worn by the gunman, begins behind the wheel of a car. A man, whose face can occasionally be seen in the rearview mirror, drives through the streets of Christchurch before pulling up in front of Al Noor Mosque, beside the sprawling Hagley Park.

The clip, which appeared to have been taken from a helmet camera worn by the gunman, begins behind the wheel of a car. A man, whose face can occasionally be seen in the rearview mirror, drives through the streets of Christchurch before pulling up in front of Al Noor Mosque, beside the sprawling Hagley Park.

[Read more here about the video, manifesto and social media posts.]

[Read more here about the video, manifesto and social media posts.]

He approaches the mosque on foot, his weapon visible, and begins shooting at people at the entrance. What follows is a harrowing nearly two minutes of his firing on worshipers.

He approaches the mosque on foot, his weapon visible, and begins shooting at people at the entrance. What follows is a harrowing nearly two minutes of his firing on worshipers.

At one point the gunman exits the mosque and fires in both directions down the sidewalk before returning to his car for another gun — which, like the others, was inscribed with numbers, symbols or messages. When he re-enters the mosque, he shoots several bodies at close range.

At one point the gunman exits the mosque and fires in both directions down the sidewalk before returning to his car for another gun — which, like the others, was inscribed with numbers, symbols or messages. When he re-enters the mosque, he shoots several bodies at close range.

After another few minutes, he returns to his vehicle and drives away.

After another few minutes, he returns to his vehicle and drives away.

“There wasn’t even time to aim, there was so many targets,” he says at one point, as the sirens of an emergency response vehicle blare in the background.

“There wasn’t even time to aim, there was so many targets,” he says at one point, as the sirens of an emergency response vehicle blare in the background.

Before the shooting, someone appearing to be the gunman posted links to a white nationalist manifesto on Twitter and 8chan, an online forum known for extremist right-wing discussions. The 8chan post included a link to what appeared to be the gunman’s Facebook page, where he said he would also broadcast live video of the attack.

Before the shooting, the gunman posted links to a white nationalist manifesto on Twitter and 8chan, an online forum known for extremist right-wing discussions. The 8chan post included a link to the gunman’s Facebook page, where he said he would also broadcast live video of the attack.

The Twitter posts showed weapons covered in the names of past military generals and men who have recently carried out mass shootings.

The Twitter posts showed weapons covered in the names of past military generals and men who have recently carried out mass shootings.

In his manifesto, he identified himself as a 28-year-old man born in Australia and listed his white nationalist heroes.

In his manifesto, he identified himself as a 28-year-old man born in Australia, and listed his white nationalist heroes.

Writing that he had purposely used guns to stir discord in the United States over the Second Amendment’s provision on the right to bear arms, he also declared himself a fascist. “For once, the person that will be called a fascist, is an actual fascist,” he wrote.

Writing that he had purposely used guns to stir discord in the United States over the Second Amendment’s provision on the right to bear arms, he also declared himself a fascist. “For once, the person that will be called a fascist, is an actual fascist,” he wrote.

Prime Minister Jacinda Ardern, speaking during a Saturday morning news conference, vowed changes to the country’s gun laws. She said that the attacker held a gun license obtained last November and that five guns were used in the attack including two semi-automatic weapons.

“Our gun laws will change, now is the time,” Ms. Ardern said, though did not elaborate on what such legislation may look like. “People will be seeking change, and I am committed to that.”

Ms. Ardern said she would be traveling to Christchurch later along with other politicians including members of the opposition. Ms. Ardern also said the attacker had not been known to either Australian or New Zealand officials.

“While the nation grapples with a form of grief and anger that we have not experienced before, we are seeking answers,” she said.

Ms. Ardern also detailed a phone call with President Trump, who offered his support. She said she asked for “sympathy and love for all Muslim communities.”

Earlier, Ms. Ardern described Friday as “one of New Zealand’s darkest days.”

President Trump, who was mentioned in the suspected assailant’s manifesto as a source of inspiration, rejected suggestions that white nationalism is a rising menace, although he suggested it might be problem in New Zealand.

President Trump, who was mentioned in the suspected assailant’s manifesto as a source of inspiration, rejected suggestions that white nationalism is a rising menace, although he suggested it might be problem in New Zealand.

“I think it’s a small group of people that have very, very serious problems,” he told reporters in Washington in response to a question. “If you look at what happened in New Zealand, perhaps that’s the case. I don’t know enough about it yet. But it’s certainly a terrible thing.”

“I think it’s a small group of people that have very, very serious problems,” he told reporters in Washington in response to a question. “If you look at what happened in New Zealand, perhaps that’s the case. I don’t know enough about it yet. But it’s certainly a terrible thing.”

Asked if he had seen the manifesto, Mr. Trump said: “I did not see it, but I think it’s a horrible event, it’s a horrible thing. I saw it early in the morning when I looked at what was happening, and we spoke, as you know, to the prime minister. I think it’s a horrible disgraceful thing, horrible act.”

Asked if he had seen the manifesto, Mr. Trump said: “I did not see it, but I think it’s a horrible event, it’s a horrible thing. I saw it early in the morning when I looked at what was happening, and we spoke, as you know, to the prime minister. I think it’s a horrible disgraceful thing, horrible act.”

Felix Kjellberg, a polarizing YouTube celebrity known as PewDiePie, distanced himself from the attacks after the man who filmed himself shooting victims at a mosque encouraged viewers to “subscribe to PewDiePie” in a video livestream.

Felix Kjellberg, a polarizing YouTube celebrity known as PewDiePie, distanced himself from the attacks after the man who filmed himself shooting victims at a mosque encouraged viewers to “subscribe to PewDiePie” in a video livestream.

“I feel absolutely sickened having my name uttered by this person,” Mr. Kjellberg, a Swede, said on Twitter.

“I feel absolutely sickened having my name uttered by this person,” Mr. Kjellberg, a Swede, said on Twitter.

Mr. Kjellberg has courted controversy by performing anti-Semitic gestures, which he calls satirical, in his videos. He has a following of 89 million subscribers.

Mr. Kjellberg has courted controversy by performing anti-Semitic gestures, which he calls satirical, in his videos. He has a following of 89 million subscribers.

Over the last 18 months, tech companies have promised stronger safeguards to ensure that violent content is not distributed through their sites. But those new safeguards were not enough to stop the posting of a video and manifesto believed related to Friday’s shooting.

Over the last 18 months, tech companies have promised stronger safeguards to ensure that violent content is not distributed through their sites. But those new safeguards were not enough to stop the posting of a video and manifesto believed related to Friday’s shooting.

A 17-minute video that included graphic footage apparently of the shooting could be found on Facebook, YouTube, Twitter and Instagram more than an hour after being posted. While Facebook and Twitter took down pages thought to be linked to the gunman, the posted content was spread rapidly through other accounts.

A 17-minute video that included graphic footage apparently of the shooting could be found on Facebook, YouTube, Twitter and Instagram more than an hour after being posted. While Facebook and Twitter took down pages thought to be linked to the gunman, the posted content was spread rapidly through other accounts.

In order to evade detection, people appeared to be cropping the video or posting the text of the manifesto as an image — techniques used to evade automated systems that find and delete content.

In order to evade detection, people appeared to be cropping the video or posting the text of the manifesto as an image — techniques used to evade automated systems that find and delete content.

Social media companies have heavily invested in those systems, with Facebook reporting last year that more than 99 percent of terrorism content by the Islamic State and Al Qaeda was found and removed through artificial intelligence.

Social media companies have heavily invested in those systems, with Facebook reporting last year that more than 99 percent of terrorism content by the Islamic State and Al Qaeda was found and removed through artificial intelligence.

A Facebook spokeswoman offered condolences to the victims and said the company was “removing any praise or support for the crime and the shooter or shooters as soon as we’re aware.”

A Facebook spokeswoman offered condolences to the victims and said the company was “removing any praise or support for the crime and the shooter or shooters as soon as we’re aware.”

YouTube said it had taken down thousands of videos related to the shooting, and asked users to help flag videos. A spokeswoman for Reddit said it was also trying to remove “any content containing links to the video stream or the manifesto.”

YouTube said it had taken down thousands of videos related to the shooting, and asked users to help flag videos. A spokeswoman for Reddit said it was also trying to remove “any content containing links to the video stream or the manifesto.”

Still, the tech companies were sharply criticized by Senator Cory Booker, a Democratic candidate for president, who said in New Hampshire on Friday that it was “unacceptable” for the companies to give “a platform to hate.”

Still, the tech companies were sharply criticized by Senator Cory Booker, a Democratic candidate for president, who said in New Hampshire on Friday that it was “unacceptable” for the companies to give “a platform to hate.”

Nasreen Hanif, a spokeswoman for the Islamic Women’s Council of New Zealand, said that little news was coming through about whether friends and relatives in Christchurch were safe, and that the country’s Muslims were anxious for updates.

Nasreen Hanif, a spokeswoman for the Islamic Women’s Council of New Zealand, said the country’s Muslims were anxious for updates.

“Nobody’s answering their phones,” she said. “We don’t know if they’re at the hospital or out of reach. Some have posted that they are safe, but others have not.”

[For Muslims in New Zealand and abroad, the massacre has drawn outrage as a brazen act of hatred borne of anti-Muslim sentiment.]

[For Muslims in New Zealand and abroad, the massacre has drawn outrage as a brazen act of hatred borne of anti-Muslim sentiment.]

Ms. Hanif said the two mosques in Christchurch had asked for help from the rest of New Zealand’s Muslims to arrange 49 funerals.

Ms. Hanif said the two mosques in Christchurch had asked for help from the rest of New Zealand’s Muslims to arrange 49 funerals.

President Recep Tayyip Erdogan of Turkey said that three Turkish citizens were wounded in the attack; the Palestine Liberation Organization’s ambassador to New Zealand said at least one Palestinian was killed; and the group Syrian Solidarity New Zealand said on its Facebook page that “Syrian refugees, including children, have been shot today.”

President Recep Tayyip Erdogan of Turkey said that three Turkish citizens were wounded in the attack; the Palestine Liberation Organization’s ambassador to New Zealand said at least one Palestinian was killed; and the group Syrian Solidarity New Zealand said on its Facebook page that “Syrian refugees, including children, have been shot today.”

A site managed by the International Committee of the Red Cross listed dozens of people who had been recorded as missing, including people from Egypt, Syria, India, Kuwait, Jordan, Afghanistan, Pakistan and Somalia.

A site managed by the International Committee of the Red Cross listed dozens of people who had been recorded as missing, including people from Egypt, Syria, India, Kuwait, Jordan, Afghanistan, Pakistan and Somalia.

Senator Fraser Anning, a member of the conservative Katter’s Australian Party, has drawn condemnation at home and abroad for linking the attack to Muslim immigration.

Senator Fraser Anning, a member of the conservative Katter’s Australian Party, has drawn condemnation at home and abroad for linking the attack to Muslim immigration.

“Does anyone still dispute the link between Muslim immigration and violence?” he tweeted.

“Does anyone still dispute the link between Muslim immigration and violence?” he tweeted.

Rebukes quickly followed from the highest levels of government in Australia and abroad. “The remarks by Senator Fraser Anning blaming the murderous attacks by a violent, right-wing, extremist terrorist in New Zealand on immigration are disgusting,” Prime Minister Scott Morrison said on Twitter. “Those views have no place in Australia, let alone the Australian Parliament.”

Rebukes quickly followed from the highest levels of government in Australia and abroad. “The remarks by Senator Fraser Anning blaming the murderous attacks by a violent, right-wing, extremist terrorist in New Zealand on immigration are disgusting,” Prime Minister Scott Morrison said on Twitter. “Those views have no place in Australia, let alone the Australian Parliament.”

Sajid Javid, the British home secretary, said that Mr. Anning had fanned “the flames of violence & extremism. Australians will be utterly ashamed of this racist man.”

Sajid Javid, the British home secretary, said that Mr. Anning had fanned “the flames of violence & extremism. Australians will be utterly ashamed of this racist man.”

Mr. Anning drew similar opprobrium last year for invoking a Nazi euphemism during a speech in Parliament, calling for a “final solution to the immigration problem.”

Mr. Anning drew similar opprobrium last year for invoking a Nazi euphemism during a speech in Parliament, calling for a “final solution to the immigration problem.”

Ms. Ardern called Friday “one of New Zealand’s darkest days.”

“What has happened here is an extraordinary and unprecedented act of violence,” the prime minister said at a news conference in New Plymouth, describing the shooting as “an act that has absolutely no place in New Zealand.”

“Many of those affected may be migrants to New Zealand — they may even be refugees here,” Ms. Ardern said of the victims. “They are one of us. The person who has perpetrated these acts is not.”

Ibrar Sheikh, the secretary of the Al Mustafa Jamia Masjid in south Auckland, described the two targeted mosques as “a United Nations” of ethnicities.

Queen Elizabeth II of Britain sent her condolences to New Zealand, which is a member of the Commonwealth. “At this tragic time, my thoughts and prayers are with all New Zealanders,” she said in a statement released on Friday.

Representative Ilhan Omar, one of the first two Muslim women elected to Congress, urged all Muslims to attend Friday Prayers and exhorted people of all faiths to join them to repudiate the white supremacist message of the New Zealand attack.

Representative Ilhan Omar, one of the first two Muslim women elected to Congress, urged all Muslims to attend Friday Prayers and exhorted people of all faiths to join them to repudiate the white supremacist message of the New Zealand attack.

“I know there was a call for people to not go,” she told reporters after addressing a climate rally in Washington. “But I said to people that is what the terrorists want us to do. That is a win for them, and so we must face the hate and terror with love and with compassion.”

“I know there was a call for people to not go,” she told reporters after addressing a climate rally in Washington. “But I said to people that is what the terrorists want us to do. That is a win for them, and so we must face the hate and terror with love and with compassion.”

Ms. Omar also said “everyone should join us in solidarity.”

Ms. Omar also said “everyone should join us in solidarity.”

The New Zealand police force had called for mosques in the country to close.

The New Zealand police force had called for mosques in the country to close.

The congresswoman, a freshman Democrat from Minnesota, has been at the center of a political tempest in the Democratic Party over remarks on Israel that critics have called anti-Semitic. She has apologized for those remarks.

The congresswoman, a freshman Democrat from Minnesota, has been at the center of a political tempest in the Democratic Party over remarks on Israel that critics have called anti-Semitic. She has apologized for those remarks.

Members of the Bangladesh national cricket team, in Christchurch for a match against New Zealand, were en route to Al Noor Mosque for Friday Prayer when the shooting began. They narrowly missed it.

Members of the Bangladesh national cricket team, in Christchurch for a match against New Zealand, were en route to Al Noor Mosque for Friday Prayer when the shooting began. They narrowly missed it.

Mohammad Isam, a journalist covering the team, reported for ESPN that at 1:52 p.m. he got a call from Tamim Iqbal Khan, one of the players.

Mohammad Isam, a journalist covering the team, reported for ESPN that at 1:52 p.m. he got a call from Tamim Iqbal Khan, one of the players.

“There’s shooting here, please save us,” Mr. Khan said, according to Mr. Isam. At first, he thought it was a prank.

“There’s shooting here, please save us,” Mr. Khan said, according to Mr. Isam. At first, he thought it was a prank.

“But he hangs up and calls again — this time, his voice starts to crack,” Mr. Isam wrote. “He says that I should call the police as there’s a shooting going on inside the mosque where they are about to enter.”

“But he hangs up and calls again — this time, his voice starts to crack,” Mr. Isam wrote. “He says that I should call the police as there’s a shooting going on inside the mosque where they are about to enter.”

Mr. Isam ran toward the mosque and saw bloodied and dazed people fleeing. In the chaos, he managed to find several players, and they eventually reconvened at the hotel. The team manager, Khaled Mashud, told reporters that players were about 50 yards from the mosque.

Mr. Isam ran toward the mosque and saw bloodied and dazed people fleeing. In the chaos, he managed to find several players, and they eventually reconvened at the hotel. The team manager, Khaled Mashud, told reporters that players were about 50 yards from the mosque.

“Had we reached even three or four minutes earlier, we probably would have been inside the mosque,” he said.

“Had we reached even three or four minutes earlier, we probably would have been inside the mosque,” he said.

“Entire team got saved from active shooters,” Mr. Khan wrote on Twitter. Another player, Mushfiqur Rahim, tweeted that he never wanted “to see this things happen again.”

“Entire team got saved from active shooters,” Mr. Khan wrote on Twitter. Another player, Mushfiqur Rahim, tweeted that he never wanted “to see this things happen again.”

Aman Singh, who works at a convenience store close to the Deans Avenue mosque, said he had heard the gunshots on Friday afternoon, and that shortly afterward people streamed past the shop, bloody and crying.

Aman Singh, who works at a convenience store close to the Deans Avenue mosque, said he had heard the gunshots on Friday afternoon, and that shortly afterward people streamed past the shop, bloody and crying.

Mr. Singh, 26, said he knew several people who worshiped at the mosque.

Mr. Singh, 26, said he knew several people who worshiped at the mosque.

“My really good friend goes there,” he said, adding that he had not been able to confirm the friend’s whereabouts on Friday afternoon.

“My really good friend goes there,” he said, adding that he had not been able to confirm the friend’s whereabouts on Friday afternoon.

Murders are rare in New Zealand, and gun homicides even rarer. There were 35 murders countrywide in 2017. And since 2007, gun homicides have been in the single digits each year except 2009, when there were 11.

Murders are rare in New Zealand, and gun homicides even rarer. There were 35 murders countrywide in 2017. And since 2007, gun homicides have been in the single digits each year except 2009, when there were 11.

But there are plenty of guns.

But there are plenty of guns.

There were 1.2 million registered firearms in the country of 4.6 million people in 2017, according to the Small Arms Survey, a Swiss nonprofit.

There were 1.2 million registered firearms in the country of 4.6 million people in 2017, according to the Small Arms Survey, a Swiss nonprofit.

New Zealand law allows any person aged 16 or older with an entry-level firearm license to keep any number of common rifles and shotguns, according to GunPolicy.org, a project hosted by the University of Sydney. Most guns can be purchased without being tracked by law enforcement officials.

New Zealand law allows any person aged 16 or older with an entry-level firearm license to keep any number of common rifles and shotguns, according to GunPolicy.org, a project hosted by the University of Sydney. Most guns can be purchased without being tracked by law enforcement officials.

A mass shooting in Aramoana, New Zealand, in 1990 — when a man killed 13 people, including two 6-year-olds, after a dispute with his neighbor — led directly to tightened gun laws, including restrictions on “military-style semiautomatic weapons.”

A mass shooting in Aramoana, New Zealand, in 1990 — when a man killed 13 people, including two 6-year-olds, after a dispute with his neighbor — led directly to tightened gun laws, including restrictions on “military-style semiautomatic weapons.”